Physical biometrics, the intrinsic physical features unique to individuals, serves as innate signatures for personal identification. Since physical biometrics is commonly tied to sensitive personal information within many national and international organizations, accurate analysis of such biometric information is important. Moreover, protection of physical biometrics against unauthorized usage is also very important. Among the various physical biometrics available for identification, the fingerprint is the most accessible and widely used. As a result, mechanisms to accurately obtain, read, as well as prevent the unauthorized retrieval of fingerprints from surfaces (i.e., anti-fingerprint surfaces) are important.
Fingerprint residues present significant biometric security and health issues. Residues imprinted by the contact of the finger on a surface consist mostly of sebum (e.g., oils or lipids), sweat (i.e., salty water), and often infectious agents such as microbes and viruses which are retained on most smooth surfaces. Therefore, development of anti-fingerprint surfaces has focused on materials that exhibit reduced adhesion for both water and oil. The conventional approach for anti-fingerprint surfaces is to utilize materials with very low surface energy (i.e., the surface chemistry approach such that liquids have relatively low adhesion on these surfaces. Over the past decade, surface coatings/functionalization strategies have been successfully developed for metals, such as stainless steel, as well as optically transparent materials, such as glass and plastics. While these surfaces show improved anti-fingerprinting property, trace amounts of remnant residues can still be attached to even the lowest surface energy materials. A recent study has shown that disease pathogens can be transferred between human and fomites through the action of contact, which can act as an important route of transmission for both gastrointestinal and respiratory illness (Julian et al. J. Appl. Microbiology 109, 1868-1874, 2010). In high-traffic security areas (e.g., airport, government buildings, schools, offices, etc.) where fingerprinting is used for identification, such health-related issues become even more important. In order to address the security and health risks, external physical contacts, such as rubbing or wiping with a cloth, are currently employed. Manual cleaning is often impractical, too costly or presents additional security risks.